When adoptees don't search, some adoptive parents and others offer this explanation:
They didn't search because they didn't need to. All of their needs were perfectly met within the context of the adoptive family.
I would like to put forth another possible explanation for why some adoptees choose not to search:
Because reaching out to someone who may not want, and may never have wanted, to have anything to do with you is freakin' terrifying!
That's just my opinion. You will have to form your own.